Arizona Republicans say GOP Sen. John McCain’s recent staff shake-up is an acknowledgment of the seriousness of his Aug. 24 primary challenge — a contest in which he remains a clear — but nervous — front-runner.

While recent polls have shown McCain with a double-digit lead over former Rep. J.D. Hayworth, in an election year in which one Senate incumbent has already been taken down and several others are facing stiff primary opposition, the departure of two top campaign officials — campaign manager Shiree Verdone and deputy manager Mike Hellon — is being viewed as proof that McCain recognizes that he faces the most serious threat of his 30-year Senate career.

Verdone and Hellon have left to run a statewide Republican Victory Committee formed with the help of a McCain ally, Yuma County GOP Chairman Phil Townsend. The committee is not aligned with the state party.

“She’s never run a campaign that I know of ever. I’m kind of shocked that he selected her in the first place,” former Rep. Matt Salmon (R-Ariz.) said of Verdone, noting that her strengths and background were related to fundraising, not strategy.

“If she’s left the campaign, I think that means John is getting very serious about the campaign,” Salmon said. “And that’s a good thing. Because I hope he wins.”

In a phone interview, Hellon said that the new victory committee has been in the works since September and is intended to make independent expenditures in the general election on grass-roots operations in races for the Senate, governorship and at least one or two House seats — but that the committee would stay out of the primary between McCain and Hayworth. He said he and Verdone have been working on setting up the committee since last summer.

The McCain campaign confirmed that the senator’s chief of staff, Arizona native Mark Buse, is now running the campaign’s day-to-day operations and that more hires would be announced in the coming weeks.

“I think Sen. McCain’s crucial decision is, does he reach out to a national campaign-manager type or does he come back to Arizona and hire somebody locally,” former Arizona GOP Executive Director Nathan Sproul said. “To me, that’s the question he has to answer. And preferably sooner rather than later.”

Tensions between the McCain camp and the state party have complicated the situation. The state party has officially taken a neutral stance in the Senate primary, but state GOP Chairman Randy Pullen has in the past had an adversarial relationship with McCain. Pullen is also the treasurer of the Republican National Committee and therefore signs off on the checks transferring funds to victory committees aligned with state parties.

An RNC spokesman left the door open to transferring national funds to the Verdone-Hellon organization or to the one officially sanctioned by the state party for November.

One GOP official familiar with the relationship between McCain and the state GOP characterized the committee controlled by former McCain aides as “direct retaliation” against the state party as a result of a squabble earlier in the year between Hellon, Verdone and Pullen.

“This has always been part of the plan,” Rogers said. “This is just part of the transition as we’re gaining ground and expanding the campaign in terms of field and other campaign operations.”

The moves, some GOP operatives said, reflect a shift in direction from a campaign run by grass-roots operatives to one that consolidates authority in the senator’s close-knit team of longtime advisers, many of whom helped him with his presidential campaigns.

McCain’s former presidential campaign manager, Rick Davis, continues to drive campaign strategy. Another longtime aide, Charlie Black, is also heavily involved as a chief consultant on strategy, as is Mark Salter, a McCain confidant and a top strategist to his 2000 and 2008 presidential campaigns.

Local Republicans aren’t surprised that McCain is turning to his national advisers to run the campaign, especially now that it’s clear he faces a viable primary challenge.

“[Pullen] and I always felt that at some point in time they would go to their national team, and it’s happened,” said Bruce Ash, a Republican National Committee member from Arizona. “I think this was always the plan. ... Sen. McCain is going to be in a very hard-fought campaign between now and Aug. 24, and he needs to bring in the big guns, and he certainly has the campaign funds to do so.”